Revolving current flotation machine



Dec. 14, 1954 c. M. ANDERSON 2,696,913

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'serve, in effect, as stators. the "impellers flows through the ports of such walls 1nto United States Patent REVOLVING CURRENT FLOTATION MACHINE Charles M. Anderson, Salt Lake City, Utah Application December 18, 1949, Serial No. 131,836

23 Claims. (Cl. 209-169) This invention relates to flotation machines and to 7 machine, thus allowing freer bubble formation and'entailing less bubble breakage.

To achieve apositive and superior recirculation of the pulp.

To speed the movement-of froth to and over the overflow lip or lips.

To eliminate all bleeder gates.

To provide a machine that is short and wide, as compared to conventional machines, and undivided into a series of individual cells, yet .one which, in effect, embodies a plurality of cells.

To increase the rate of. recirculation of a flotation pulp, and the .rate at which air is added thereto, as such pulp travels.progressivelythrough a machine.

To decrease the surface area of a flotation pulp as itprogresses through a machine.

To greatly shorten the froth-receiving launders, so they may be sloped considerably more than is feasible with conventionalmachines, thereby reducing the amount of water necessarily added.

To enable the placing of relatively wide walkways on top, instead of along the sides, of a machine, thereby economizing space and affording more convenient access during operation.

To considerably reduce the extent of inside wall surface of a flotation machine, so that more bubbles reach the surface of the pulp.

To considerably reduce the size of a flotation machine of given capacity, thereby reducing the floor area required in the mill.

To provide a new and improved flotation system utilizing gravity flow of pulp from conditioner to flotation machine and from circuit to circuit.

In the attaining of these objects of the invention, I provide a series of impellers within an undivided'agitation chamber defined longitudinally by oppositely disposed and ported, rectilinear, pulp-directing walls which Pulp discharged forcibly from respective bubble chambers, which are longitudinally coextensive with'the walls. The flow ofaerated'pulp across the bubble chambers is thus-along respective paths which are disposed in side-by-side parallel relationship along the length of the machine. Respective froth overflow lips are provided along the tops of the outer longitudinal walls of the bubble chambers, such lips being disposed in parallel relation to the ported walls and across the widths of the respective bubble chambers therefrom.

Thus, the flow of aeratedpulp is at substantially right Q angles to such froth overflow lips. Walkways extending longitudinally ofthe machine may be placed above such bubble chambers.

A continuous and undivided pulp feed compartment or conduit extends longitudinally of the machine immediately below the agitation chamber, andopens into ice the undersides of the respective impellers. Such feed compartment communicates laterally with the respective bubble chambers, and provides for recirculation of the pulp along respective paths of revolution comprehending the outward flow paths of aerated pulp.

The ports of the pulp-directing walls become progressively more numerous and -more-closely spaced from the feed end to the discharge end of the machine, in order to progressively increase the rate of recirculation of the pulp and the rate at which air is added thereto.

The usual bleeder gates are eliminatedby constructing the tailings discharge so that sands are forced back into the recirculating pulp through cleaner ports disposed at the discharge end of the machine. Accumulation of sands is effectively prevented by this expedient.

Hydrostatic heads are advantageously maintained at different levels in the machine, as will hereinafter appear, for aiding in the operation thereof.

In the flotation system, I provide a single machine of suitable capacity for each recovery circuit, the same being arranged, together with-the respective conditioner units, in downwardly stepped series, so that flow of pulp through the system will be by gravity.

Further objects and features will become apparent from the following detailed description of the presently preferred specific embodiments illustrated inthe accompanying drawings for the purpose 'of exemplifying the generic characteristics 'of the invention.

in the drawings:

Fig. 1 represents a top plan view-of the machine;

Fig. 2, a longitudinal vertical section taken on the line 2-2 of Fig. 1;

Fig. 3, a transverse vertical section taken on the line 33 of Fig. 2;

Fig. 4, a similar view taken on the line 4-4 of Fig. 2;

Fig. 5, a fragmentary horizontal section taken on the line 55 of Fig. 2, and drawn to an enlarged scale;

Fig. 6, a diagrammatic plan view of a flotation system utilizing the machine of the above figures in each of its three recovery circuits;

Fig. 7, a diagrammatic side elevation of the same;

Fig. 8, a view corresponding to that of Fig. 3, but drawn to a reduced'scale and illustrating a machine utilizing concrete construction, .a double row of impellers, and adjustable stators;

- Fig. 9, a fragmentary horizontal sectiontaken on the line 9-9 of Fig. 8;

Fig. 10, a fragmentary portion of Fig. 8 including an impeller and stator drawn to an enlarged scale to illustrate minor details;

Fig. 11, a side elevation of the structure appearing in Fig. 10, the view being taken from the right in Fig. 1.0;

Fig. 12, a fragmentary portion of Fig. 8, including the left-hand impeller and stator, and illustrating the stator in an alternate adjusted position;

Fig. 13, a similar view, but including the right-hand impeller and stator, and illustrating the stator in a different adjusted position.

Fig. 14, a fragmentary top plan view of a somewhat different arrangement of tailings discharge applied to the machine of Figs. 1 through 5, the-view comprehending the tailings discharge portion of one machine and the pulp inflow portion of a succeeding machine;

Fig. 15, a transverse vertical section taken on the line 15-15 of Fig. 14;

Fig. 16, a fragmentary, longitudinal, vertical section taken on the line 1616 of Fig. 14; and

Fig1.517, a similar section taken on the line 17'17 of Fig.

Referring to the drawings: the flotation machine of Figs. 1 through 4 is'illustrated as constructed of structural steel and equipped with a single row ofimpellers.

Pulp agitation In accordance with the novel structural concepts of the invention, the machine includes a series of impellers, which maybe of conventional type, such as the vertically mounted squirrel cage impellers 10 illustrated, the same being positioned Within an undivided, elongate, agitation chamber 11 defined longitudinally of the machine by ing as stators.

Pulp feed The floor 13 of the agitation chamber 11 is spaced above the bottom 14 of the machine, and rests upon oppositely-disposed, longitudinal stringers 15, which are conveniently structural steel channels, as illustrated. A longitudinally extending compartment 16 is thus formed immediately below the agitation chamber 11.

Such compartment 16 opens at one end into a pulp feed box 17, and opens at the other end through suitably arranged ports into the bottom portion of a tailings discharge box 18, the former being divided from the agitation chamber by an end wall 19 of the machine, and the latter by an end wall 20 of the machine. A series of apertures 21 through the floor 13 of the agitation chamber establishes passage from the compartment 16 to the interiors of the respective impellers 10. Thus, tihe compartment 16 becomes, in effect, a pulp feed conuit.

One of the three different hydrostatic heads in the machine during operation thereof is established by the level L-1 of pulp maintained in the feed box 17.

Bubble columns and froth discharge Defined laterally of agitation chamber 11, by respective side walls 22, Fig. 3, and the end walls 19 and 21) of the machine, are bubble chambers 23 having froth overflow lips 24, respectively, leading into respective launders 25. The side Walls 22 preferably slope upwardly and outwardly from bottom 14 of the machine, so as to establish broad froth collection zones F superficially of the bubble columns 26 during operation of the machine.

The pulp-directing walls or stators 12 are of suitable abrasive-resistant material, such as rubber or a rubber composition. Preferably, pure gum natural rubber at least /2 inch in thickness is employed for the purpose. Such stators are provided with numerous relatively small ports 27, which are desirably staggered in position and progressively increase in number per unit length from the feed end of the machine to the discharge end thereof, the exact size and spacing of the ports being determined in any given instance according to accepted engineering practice with respect to rotor-stator design. In a machine having the general proportions of that illustrated, ports approximately one inch square are appropriate. The walls 12 are in most instances sloped upwardly and inwardly, as shown, so that the pulp will be directed somewhat upwardly as it flows outwardly through the ports, as indicated by the respective pulp-flow circuits 28 in Fig. 3.

It should be noted that the flow of aerated pulp from the ports 27 of the pulp-directing Walls or stators 12 is substantially straight-line and parallel in character. To take best advantage of such character of flow of the aerated pulp, the bubble chambers 23 and froth overflow lips 24 are longitudinally coextensive with and parallel to the agitation chamber 11 and stators 12.

Another of the three different hydrostatic heads existing in the machine during operation thereof is established by the level L2 of the aerated pulp in the bubble chambers 23.

Pulp recirculation Impeller assemblies and air intake Forming structure upon which the several impeller motors are mounted, as well as upward continuations 11a of the agitation chamber 11 at the respective impellers 10, are longitudinally extending beams 30, Fig. 3, advantageously being structural steel channels, as shown. The lower out-turned flanges thereof receive and support, in this embodiment, the upper margins of the respective end to the tailings disstators 12, as by means of longitudinal fastening elements 31. Between such beams 3t), at intervals determined by the positions of the several impellers, are secured box-like partitions 32, Figs. 2 and 5, and across the tops thereof and of the intervening spaces are secured cover plates 33.

Supporting standards 34 for the respective impeller assemblies are secured to and rise from the cover plates 33 at the said intervening spaces. Such standards are conveniently I-bearns. Bearings 35 and 36, projecting out over the spaces from such standards 34, serve to rotatably mount respective impeller shafts 37, which are driven from respective motors 38 through conventional belting arrangements indicated at 39. The motors 38 are conveniently mounted on the respective frames 34 by means of respective brackets 40.

Air is drawn into the impellers 10 through respective tubular conduits 41, which extend vertically through cover plates 33 and between adjacent partitions 32 to terminations appropriately short of the upper ends of the impellers.

The third hydrostatic head existing during operation of the machine is established within the upward continuations 11a of the agitation chamber 11 by the pulp level L3, Fig. 3.

Tailings discharge The tailings pass from bubble chambers 23 into the tailings discharge box 18 by way of discharge openings 42, Fig. 4. The greater part of any sands tending to accumulate at the bottom of such discharge box 18 are recirculated into feed conduit 16 through cleaner ports 43, Figs. 2 and 4.

As illustrated in Fig. 4, the tailings discharge box 18 is divided horizontally by a septum 44, through which a tubular Weir 45 is raised or lowered by means of a handwheel 46. The upper open trough portion 18a of the box has a tailings discharge pipe 47 leading therefrom.

A valved drain 48 leads from the bottom of the lower portion 18b of the box, to permit periodic flushing of any sands which may accumulate.

Access It will be noted that the superficial froth collection surfaces of the bubble chambers are relatively broad, and permit the placement thereover of walkway gratings 4'5, Figs. 6 and 7. Such gratings are supported at their ends by the end walls 19 and 20 of the machine, which rise a sufficient height to properly position the gratings relative to the froth accumulations.

Thus, access to the working parts of the machine is conveniently attained, and considerable space is saved over the conventional manner of placing walkways.

Operation in operation, pulp is continually fed into conduit 16 from pulp feed box 17, and is sucked up into the impellers 10 through apertures 21, being aided, of course, by the hydrostatic head at level L-1.

Aerated pulp is flung radially outwardly by the impellers, and passes toward and through the ports 27 of stators 12, from where it travels directly outwardly along substantially straight and parallel lines, without structural interference. The hydrostatic head at level 1:3, which is established by the action of impellers 10, plays an important part in forcing the aerated pulp through the stator ports.

The above-mentioned straight line, parallel flow of the pulp, and the recirculation thereof along the flow circuit or paths of revolution 28, insure thorough aeration and efficient, high recovery of metallurgical values.

The tailings which pass through discharge openings 42 into tailings discharge box 18 are thoroughly impoverished.

Froth is recovered in conventional manner by the respective launders 25 after discharge over the lips 24.

The system The machine of the invention makes possible the provision of flotation systems having unique attributes and advantages.

The system illustrated diagrammatically in Figs. 6 and 7 is typical, and includes three circuits for the successive recovery of lead, zinc, and iron.

Conditioner tanks 50 for the respective successive circuits are arranged at approximately the same level as the flotation machines 51 which they serve, so that umping is eliminated, and flow from the conditioner tanks to the corresponding flotation machinesv is accomplished througn respective feed pip.3 52. On the other hand, flow Irom the tailings box of one machine to the conditioner tank of a successive circuit is accomplished by gravity through a pipe 53.

Respective cleaner cells 54 are interposed as illustrated, and the walkway gratings 48 of the respective machines are joined by walkway flights 55'.

The entire system is stepped downwardly from a first level, corresponding to the first recovery circuit, through successive levels corresponding to successive circuits.

This arrangement permits a great saving in space over conventional systems, wherein the conditioner tanks are placed on a lower floor of the mill and contents thereof are pumped into the feed box of the rougher cell of the corresponding recovery circuit. In such conventional systems, one circuit occupies approximately the same space as all three circuits of the present system.

Furthermore, by reason of the walkway gratings being placed as they are with respect to the component units of the system, operation of the several'circuits is made easier. An entire circuit can be seen by an attendant from one vantage point.

Concrete construction The machine and system of the invention are well adapted for reinforced concreteconstruction in the obtaining of longer operative life than is possible with machines fabricated from steel plate.

As illustrated in Figs. 8 through 13, where an installation having a series of machines disposed side-by-side is shown, side walls 69, bottom 61, and launders 62 are constructed integrally, throughout the series, of reinforced concrete, the overflow lips 63 being advantageously provided by superimposed structural steel members, as shown.

Likewise, the end walls of the machine, as indicated at 64, are integral with and serve to support a longitudinally extending slab 65, through which air shafts 66 for the respective impellers 10 extend. Such end walls and slab are, as illustrated, of reinforced concrete.

As here shown, the impellers 10 are arranged in staggered relationship within double, parallel rows, see especially Fig. 9. This exemplifies the versatility of arrangement possible in the machine of the invention, without sacrificing advantageous operative characteristics thereof.

The pulp feed conduit, indicated here at 67, is defined by walls also made of reinforced concrete. Thus, all of the essential structural components of the machine can be made highly wear-resistant and substantially permanent.

Adjustable stators In this embodiment of the invention, I have chosen to illustrate how the pulp-directing walls or stators 68. of the machine may be made adjustable, so the recirculation paths of revolution may be modified for any given run of the machine to suit special requirements for maximum recovery.

As shown in Figs. 10 and 11, each stator 68 comprises a sheet of flexible and resilient abrasion-resistant material 68-1-preferably the pure, natural gum rubber mentioned hereinbeforesecurely fixed, as by means of bolts 69, to a longitudinally-extending and adjustable frame 70 which is pivoted, preferably centrally thereof, to the opposite end walls of the machine. Ample marginal flaps 68-1a overlap the frame 70, and bear outwardly against the overlying and underlying walls, respectively, to provide seals longitudinally of the agitation chamber 71.

A manually-operable handle 72, secured to the frame 70 and extending upwardly for convenient access by an attendant, provides for angular adjustment of the stator to either side of the vertical within a range indicated generallv by Figs. 12 and 13.

The adjustment is guided and fixed by any suitable means, for example, by a slotted guide 73, Fig. 8, and anchor screw 74.

Alternative tailings discharge In Figs. 14 through 17 is illustrated an alternative form of tailings discharge, the same being applicable in its essentials to any of the foregoing embodiments of the invention, but, for illustrative purposes, being here shown 6 in connection with the steel construction of Figs. 1 through 5.

As illustrated, the side walls 22 defining bubble chambers 23 are extended, as at 22a, to comprehend the tailings discharge box, here indicated 80-. Such tailings discharge box 80 has its inflow passages 81 from respective bubble chambers 23 disposed laterally thereof. Only the several sand openings 82 from pulp feed compartment gr cc sduit 16 enter through the front wall 83 of the Above the inflow passages 81, tailings discharge box 80 is open to provide free upward passage for tailings to an outflow level established by a tubular Weir 84. Such outflow level is preferably and normally established at substantially the level of pulp in the bubble chambers.

The weir 84 extends through a horizontally-disposed partition 85, which divides the discharge box 80 into an upper chamber 80a and a lower chamber 8%. The lower end of the discharge box 80 has an outlet 86; which, in the case of an installation involving aseries of machines, as illustrated in Fig. 16,- opens directly into the pulp'feed compartment or conduit 16 of thesucceeding machine. Thus, the upper chamber 80a of the discharge box 80 serves directly as a tailings discharge box, while the lower chamber 80b may serve, in effect, as a pulp feed box for a succeeding machine of a series.

In this embodiment, horizontal baffles 87 extend from the junctions between stators 12 and pulp feed compartment or conduit 16 at respectively opposite sides of the machine, for positively guiding pulp recirculation. This feature is optional in the several embodiments of the invention.

Conclusion While three different. hydrostatic heads are advantageously maintained by three diiferent pulp levels established during operation of the machine in certain forms of the invention, it can be seen from the concrete construction of. Figs. 8 tol3 that in some instances structural considerations will control. Thus, in the particular concrete construction illustrated, no provision is made for a pulp level corresponding to L3 in the first-described embodiment, thereby eliminating the hydrostatic head ordinarily maintained by such level of pulp in the machine. In this instance, the centrifugal flinging action of the impellers, alone, forces the aerated pulp through the stator ports.

It has been convenient to illustrate theseveral embodiments as. comprising a container for pulp in which the aeration chamber is defined along the central longitudinal axis of the container, forming double bubble chambers symmetrically flankingthe aeration chamber at opposite sides thereof. It should be realized, of course, that a single bubble chamber may be utilized where conditions warrant, and, further, that the sides of the container may slope at various angles or may be vertically disposed, all as a matter of choice in particular instances.

Whereas this invention is here illustrated and described with respect to a certain presently preferred specific embodiment thereof, it should be understood that various changes may be made therein and various otherforms may be constructed on the basis of the teachings hereof, by those skilled in theart, without departing from the protective scope of the following claims.

I claim:

l.A flotation machine, comprising an elongate container for pulp; a ported wall extending longitudinally of the container, as a stator, defining within said container an elongate agitation chamber flanked by an elongate bubble chamber, both said aeration chamber and bubble chamber being substantialy uninterrupted and undivided along their lengths; a series of aeration impellers operatively disposed within and spaced apart along said agitation chamber; a froth overflow lip formed along the top of the container side wall which defines, in part, said bubble chamber; wall means defining an elongate compartment extending longitudinally beneath said agitation chamber, said compartment opening into the agitation chamber at the respective impellers and serving as a pulp feed conduit; means for feeding pulp into one end of said compartment; passage means extending from said bubble chamber into said compartment, for pulp recirculation; and tailings discharge means leading from said bubble chamber.

2. The combination recited in claim 1, wherein the container side wall and the stator wall is substantially parallel longitudinally of the machine.

3. The combination recited in claim 1, wherein the stator wall is fixed in position and slopes upwardly inwardly of the machine, so that aerated pulp is directed diagonally upwardly across the bubble chamber.

4. The combination recited in claim 1, wherein the ports of the stator wall and the passage means from bubble chamber to the pulp feed conduit increase in number per unit area from the pulp feed and to the tailings discharge end of the machine.

5. The combination recited in claim 1, wherein the stator wall is adjustable about a longitudinal axis.

6. The combination recited in claim 1, wherein airintake conduits extend from above the highest working level in the machine down to the respective impellers; and wherein respective wall means surrounding said airintake conduits provide upward continuations of the agitation chamber.

7. The combination recited in claim 6, wherein the impellers are of squirrel-cage type.

8. The combination recited in claim 1, wherein a double row of impellers extend longitudinally of the agitation chamber.

9. The combination recited in claim 1, wherein the tailings discharge means comprise a tailings discharge box at the end of the machine which is opposite the pulp feed end; and passage means from the bubble chamber into said tailings discharge box.

10. The combination recited in claim 9, wherein openings for the passage of sand are provided between the tailings discharge box and the adjacent end of the pulp feed compartment.

11. The combination recited in claim 10, wherein the tailings discharge box is divided by a septum into an upper compartment and a lower compartment, and a tubular weir establishes flow communication between said compartments.

12. The combination recited in claim 11, wherein the passage means from the bubble chamber enters the upper compartment of the tailings discharge box; and a tailings outlet is provided in the lower compartment.

13. The combination recited in claim 1, wherein opposite end walls of the container extend well above the froth overflow lip; and longitudinally-extending walk- Wafi structure is supported by said opposite container end wa s.

14. The combination recited in claim 1, wherein a substantially horizontal, longitudinally extending baffle projects out across a portion of the width of the bubble chamber from between the agitation chamber and the pulp feed compartment for positively directing pulp recirculation.

15. The combination recited in claim 1, wherein the tailings discharge means comprise a tailings discharge box at the end of the machine which is opposite the pulp feed end; wherein the bubble chamber is extended so as to flank said tailings discharge box; and wherein the tailings discharge means further comprises laterally disposed passage means from said bubble chamber into said tailings discharge box.

16. A flotation machine comprising an elongate container for pulp; two oppositely disposed, ported walls extending longitudinally and spaced apart transversely of the container, as stators, to define an elongate agitation chamber extending along the longitudinal central axis of the container, and two longitudinally extending bubble chambers flanking said agitation chamber at respectively opposite sides thereof, the said agitation chamber and the said bubble chambers being substantially uninterrupted and undivided along their lengths; a series of aeration impellers operatively disposed within and spaced apart along said agitation chamber; froth overflow lips formed along the tops of the respective side walls of the container which define, in part, said bubble chambers; an elongate compartment extending longitudinally beneath said agitation chamber, said compartment opening into the agitation chamber at the respective impellers and serving as a pulp feed conduit; means for feeding pulp into one end of said compartment; passage means extending from said bubble chambers into said compartment for pulp recirculation; and tailings discharge means leading from said bubble chambers.

17. The combination recited in claim 1, wherein the compartment defining the pulp feed conduit rises above the level of the bottom of the bubble chamber.

18. The combination recited in claim 17, wherein the wall means defining said compartment is ported laterally to provide the passage means extending from said bubble chamber into said compartment.

19. The combination recited in claim 16, wherein the compartment defining the pulp feed conduit rises above the level of the bottom of the bubble chamber.

20. The combination recited in claim 19, wherein the wall means defining said compartment is ported laterally to provide the passage means extending from said bubble chambers into said compartment.

21. In a flotation machine provided with pulp-recirculating passage means, tailings discharge structure, comprising a box; a septum dividing said box substantially horizontally into an upper compartment and a lower compartment; a tubular weir extending through said septum and establishing flow communication between said compartments; tailings inflow passage means leading into one of said compartments; tailings outflow passage means leading from the other of said compartments; and cleaner ports establishing flow communication between said one compartment and said pulp-recirculating passage means.

22. The combination recited in claim 21, wherein the tailings inflow passage means leads into the lower compartment, and the said tailings outflow passage means leads from the upper compartment.

23. The combination recited in claim 21, wherein the said tailings inflow passage means leads into the said upper compartment, and the said tailings outflow passage means leads from the lower compartment.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,413,723 Groch Apr. 25, 1922 1,457,077 Janney May 29, 1923 1,744,785 McTaggart Jan. 28, 1930 1,942,803 Daman -2 Jan. 9, 1934 1,963,122 Fagergren June 19, 1934 2,054,249 Fagergren Sept. 15, 1936 2,143,669 Weinig Jan. 10, 1939 2,168,942 McClave Aug. 8, 1939 2,178,239 McKenna Oct. 31, 1939 2,252,576 MacIntosh Aug. 12, 1941 2,259,243 Daman Oct. 14, 1941 2,466,995 McMurray Apr. 12, 1949 FOREIGN PATENTS Number Country Date 584,306 Great Britain Jan. 13, 1947 681,212 Germany Aug. 31, 1939 OTHER REFERENCES Denver Equipment Company Bulletin No. F10.B29 on Denver Sub-A Flotation, received in Patent Oflice August 5, 1949. 

